The use of vertical structures to obtain dense memories is a practice known to those skilled in the art. It has notably been implemented with flash memories as is for example described in the document US 2006/0186446.
More recently, a similar structure has been proposed, but this time using resistive memories. This is notably detailed in the document “Study of Multi-level Characteristics for 3D Vertical Resistive Switching Memory”, Scientific Report (2014). As illustrated in FIG. 1, this document describes a memory device including a plurality of first electrodes, designated flat electrodes EP, each first electrode EP of the plurality of first electrodes EP being separated from two adjacent electrodes EP of the plurality of first electrodes EP by a layer of an insulating material CI. The device also comprises at least one pillar PI, designated vertical pillar PI, extending essentially along an axis perpendicular to the planes defined by the flat electrodes EP, the pillar PI including a third electrode EV, designated vertical electrode EV and an information storage layer CSI, the information storage layer CSI covering a surface of the vertical electrode EV. In addition, in this device, each flat electrode EP is laid out so as to form a memory point PM with the vertical pillar PI. Thus, for each pillar PI, a plurality a memory points PM constituting a memory cell is obtained.
In such a device, it is possible to associate a surface with each memory cell. However, only a part of this surface is actually used for the storage of information and the remainder of the surface occupied by a memory cell does not support any functionality. In addition, if it is wished to add a battery to such a memory device, it is necessary to produce the battery during additional steps on another part of the substrate used for the manufacture of the memory device, the latter further occupying an additional surface.
Certainly, it has recently been demonstrated, in the article of Nature Communications, Valov et al., 2784, 2013, that a battery effect can be measured in a resistive random access memory type component. This article discloses that a resistive random access memory type component, the operation of which is based on the occurrence of oxidation-reduction reactions, makes it possible to make an intrinsic electromotive force or emf stemming from the movement of ions appear.
The authors thus make the experimental and theoretical demonstration of the existence, in this type of component (here a resistive random access memory), of an electromotive force resulting from the creation of different chemical potential gradients between the two electrodes of the component when no filament type conductive path is created between them. This electromotive force is considered as a voltage generated by the component and may be obtained by dissolution of an active electrode in the active zone (here an electrolyte) by an electrochemical process, which the authors consider as being the demonstration of a “nano-battery” effect.
However, the authors conclude that the electromotive force observed only suggests the existence of a nano-battery effect and propose the extension of theoretical models able to describe the physical phenomena governing the operation of resistive random access memories in integrating this effect. The article thus does not disclose all the characteristics necessary for the operation of a memory point for the storage of energy and does not describe the concrete feasibility of such an application. In particular, the electromotive force is only measured in the oxidised state, which would correspond uniquely to the discharged state of a battery. In addition, no demonstration of the repeatability or the reversibility of the phenomena described within the component is made. It is important to note that knowledge of this application (which can in no way be deduced from the documents cited previously) would lead to the use of a part of the memory points as place for storage of energy without resolving the problem of the unused surface.
There thus exists a need for a memory device of which the whole of the surface of a memory cell is used to fulfill a function. A need further exists for such a device making it possible to easily integrate a battery.